My 1994 Mercedes E320 wagon has this loud motor sound and where does that loud sound comes from? Is it the exhaust, manifold, catalytic converter, muffler, losing compression, defective 02 oxygen sensor, etc? There is no check engine light (CEL) showing. However, on the self-diagnostic test (DSM) 16 pin, it shows the troubleshooting light of 4 only, meaning the MAF sensor. I had this issue of MAF for quiet some time but I don't think it is related to the loud motor sound.

When I started the car the first time, at first, normal, then driving a short distance and of all sudden loud noise coming from the engine? I cannot pin point the exact location of the loud sound. It sounded like a hot rod.


I do notice a difference in the rpm on the dashboard. When I floored the accelerator, normally the rpm at around 4400 would rattled which is normal. Now the rpm is free floating over to the maximum without rattling. Is it a rpm issue? If so, what would be the culpit? I am somewhat baffled by this issue and scratching my head as to what is the source of the problem. Any ideas anyone? I appreciated some feedback on this issue. Thanks.